The invention relates to a lifting door with a slatted armor which is movable vertically upwards from a closed position into an open position relative to a door aperture.
A known example of a lifting door is a rolling door which functions as a vertically opening closure of a walk-through or drive-through door aperture. Such lifting door conventionally consists essentially of a rolling armor, having mutually pivotally connected slats which are guided into the closed position at the two side edges of the door aperture by means of vertical guide rails, a winding shaft to which the rolling armor is fastened for moving in response to an electromotive drive, and a catch device which prevents the rolling armor from crashing down in the event of a failure of the drive.
The rolling armor functioning as the part of a rolling closure which closes off and protects the door aperture consists of slats, generally profiled parts, for example extruded aluminum materials, connected to one another in an articulated manner. The height of the individual slats is, generally approximately 80 to 120 mm. These profiled parts are usually provided as push-in profiles which, on account of their shape, are connected to one another in an articulated manner, without further connecting members, to form the rolling armor. In a typical aluminum extruded profile, the joint is designed, for example, as a cup and web, so that, with the profiles pushed into one another, the joint thus formed can absorb and withstand the forces occurring when the rolling armor is being wound up. The connection of the slats which is shaped to form a joint has, generally, a large play.
Moreover, with the profiles pushed into one another, dirt and water are prevented from settling in the joints and sufficient sealing against wind is provided.
The roll layers on the winding shaft are formed by the interconnected profiles which have a specific profile height. Each profile is laid onto the edge of a profile which projects most of the layer located underneath it. The direction which a profile assumes within its roll layer in the cross-section of the roll depends on the bearing point of the profile. By its randomly assumed position, it also determines, in turn, the arrangement of the next profile connected to it. This results, with the roll wound up, in an irregular layered arrangement of the individual profiles of the rolling door. It follows from this, that, for example, only a single edge of a single profile of the rolling door supports the entire load of the armor part still hanging freely, as a consequence of which considerable edge pressures can occur.
As a safeguard against lateral displacement, head pieces or end pieces, which run in corresponding vertical guide rails each having a generally U-shaped cross-section, are, typically, fastened laterally to the profiles of the rolling door. These vertical guides are widened in a funnel-shaped manner at their upper entrance, so that the rolling armor, when being unrolled, can run perfectly into the vertical guide without the risk that it will become caught.
The rolling armor is fastened by means of its initial profile to the winding shaft in such a way that, with the door closed, the fastening is located on the side of the shaft facing away from the armor. Thus, the armor or the end plates lengthens the armor loop round the shaft by at least 180.degree.. This ensures that the armor is held largely by frictional forces, and therefore the full dead weight of the armor does not act upon the suspensions. The door is closed when the tail profile rests sealingly on the lower edge of the aperture, i.e., generally on the ground. Moreover, the rolling armor should not collapse. The entire armor, with the exception of the tail profile, thus remains hanging as a load on the shaft or shaft axle. The rolling door thereby differs fundamentally from the roller blind which is usually provided as an additional closure of an aperture.
In the open position of the rolling door, the rolling armor rolled up onto the winding shaft is located in the lintel region of the door aperture. The drive usually lies protected behind the lintel and therefore cannot be damaged by vehicles when they drive through the door aperture. An electric motor is typically provided as a drive, and furthermore a hand-operated drive is available for temporary operation.
An electric drive is employed and the rolling-door shaft is driven at a constant rotational speed, i.e., at a uniform angular speed. The rolling armor fastened to the shaft is thereby raised and wound up onto the shaft. A critical factor in the lifting speed is the particular effective winding radius which is increased continuously during the winding, since the lower parts of the rolling armor are laid onto the already wound upper parts. Since the lifting speed changes in direct proportion to the roll radius, a rolling door first runs upwards slowly, becoming more and more rapid in the upward direction. In a closer consideration of the kinematic conditions, and allowing for the thickness and height of the profiles, the rolling-door roll must be viewed as a polygon. During the winding, the profiles are first laid onto the round winding shaft. The straight profiles form a polygon thereon. At the same time, the corners of the polygon are further from the center point of the shaft than the centers of a side of the polygon. When the shaft of the rolling door is rotated at a constant angular speed, the rolling armor is pulled up with a lever arm corresponding to the length to the corner point of the polygon and at the lifting speed corresponding to this lever-arm length and in the next moment with a lever arm corresponding to the length to a side of the polygon and at the lifting speed corresponding to this. The lifting speed is directly proportional to the particular effective lever arm occurring discontinuously and irregularly and is therefore characterized, during the winding of the rolling armor, by correspondingly pronounced and sudden fluctuations. This is accompanied by mass accelerations and decelerations of fluctuating amounts of the still unwound mass of the rolling armor. These mass accelerations also enter the gear of the drive motor, which gear has to be designed for an appropriate degree of non-uniformity, since breakdowns can otherwise occur. These accelerations are smaller, the thicker the rolling-door roll becomes, i.e., the more the polygon approximates a circle. However, since the highest mass accelerations and decelerations occur when the rolling armor is closer to its closed position, these forces are therefore still mutually augmented as a result of the appreciable dead weight of the rolling armor.
The accelerations and decelerations of the masses of the unwound rolling armor have the effect of vibrations. These vibrations also act by way of the winding shaft on the building, and therefore it must be ensured in the static calculation of the building that the natural vibration frequency remains outside the rolling-door frequencies. Otherwise, the lifting speed of the rolling door has to be drastically reduced. At a uniform angular speed of the rolling-door shaft, with a thickening rolling-door roll the frequency of the vibrations will increase and their amplitude decrease. This means, conversely, that the generation of sound during the actuation of the rolling door becomes greater, the further the rolling armor comes down.
In addition to the abovementioned irregularities in the lever-arm ratios during the winding of the profiles in the form of polygonal courses, in the case of the hitherto known rolling doors there is a further irregularity which also leads to extremely problematic kinematic conditions. Since the driven shaft of a rolling door cannot exert any pressure forces on the rolling armor, it is necessary to ensure that, in the raised state, the falling weight of the freely hanging part of the rolling armor, together with the lower rail, is greater than the friction of rest. Only thus is the armor automatically set in motion, as a result of its own gravitational force, when the shaft is driven in the downward direction. The least friction for the armor is provided when it runs in the raised state vertically into the guides. This type of mounting is called "normal stance". In proportion as the rolling armor runs down, the roll diameter decreases. The armor then runs increasingly more obliquely into the entrances of the guides. When the rolling armor has run down completely, but, as is customary with rolling doors, still hangs with a pull on the shaft, the entire load of the rolling armor in some circumstances hangs only on a single profile of the profiles still located on the shaft. If the vertical cross-section of a rolling door is considered, it will be seen that the pull of the entire dead weight of the armor is not in the door plane, but in the rectilinear connection between the bottom piece and the effective roll radius. The rolling armor will therefore experience deformation in the middle between the guides, in order to come as close as possible to the path of the tensile stress. However, the profile ends are held by the guides and cannot follow the line of tensile stress. Whereas the tensile stress resulting from the dead weight of the rolling armor pulls the armor on the upper part out of the door plane in the direction of the shaft, the guides bend the profile ends towards the door plane again. However, the individual profiles are thereby subjected not only to bending stress, but also to torsional stress. The highest bending and torsional moments occur at the entrance.
In order to reduce the sealing problems involved in the "normal-stance" type of mounting, it was proposed to limit the bending by attaching a pressure shaft. However, this entails a more unsteady and noisier running of the rolling door (see Horst Gunter Steuff, "Das Rolltor", ["The Rolling Door"], Dusseldorf, Werner Verlag GmbH, 1987, page 93).
The above-described unfavorable kinematics of the rolling door which has been known (and hitherto scarcely changed) in its basic features for more than one hundred years is to be seen as the main reason for the generation of a large amount of noise during running and, in the final analysis, also for the insufficient high-speed property of the rolling door. The running noises originating essentially from the profile joints occur mainly during the upward travel of the rolling door and then also to an especially pronounced extent in the lower third of the door aperture, in so far as the rolling door has a "normal stance". The noises arise in the vicinity of the lead-in, where the profiles bend, are subjected to high pulls and are rotated in the joints.
Although the hitherto known rolling door, on account of the non-positive and positive connections of its slats, was for a long time considered to be the most cost-effective solution in terms of sealing against wind pressure and safety against unauthorized opening, the poor high-speed properties of the conventional rolling door were recognized at an early stage as being disadvantageous when it was used as an industrial door. The running speeds of a conventional rolling door are approximately 0.25 to 0.35 m/s.
In the industrial sector, high-speed rolling doors having a full-surface door leaf made of flexible material, which can be wound onto a winding shaft or winding drum, have also proved successful as an additional aperture closure. Moreover, rolling doors of this type, whilst offering a suitable choice of flexible material, afford the advantage of optical transparency. Macrolon foils or soft PVC foils, for instance, are in widespread use. However, this advantage over opaque material disappears in time, since the visual transparency is impaired as a result of the penetration of dust and the like during the winding up of the foil, and the associated scratching of the surface.
In view of the limited amount of space available above the lintel region and the large core diameter of the shaft, conventional in foil-type rolling doors, the foils in this type of rolling door have to be as thin as possible, since the overall winding diameter otherwise becomes too large. Furthermore, the provision of thinner foils at the same time allows the door leaf to run at higher speed on account of the easier windability. The small thickness of the foils and accordingly the low dead weight of the door leaf nevertheless lead to a reduced wind-resisting strength. It was proposed, as a remedy for this, to provide additional weight in the form of a closing profile, arranged on the lower edge of the door leaf, or spring-loaded tensioning belts which run over deflecting rollers mounted on the ground.
The greatest disadvantage of the foil-type rolling doors therefore arises from the behavior of the door leaf under wind pressure, which approximates more closely to the behavior of a sail than to the behavior of a plate. Since the door leaf is supported only on the winding shaft, under wind load the door leaf becomes considerably distended and bulged and is consequently also lifted. Rolling doors of this type are therefore to be considered only as an additional closure for a door aperture also in view of deficient safety against unauthorized opening.
Furthermore, so-called sectional doors, e.g. U.S. Pat. No. 3,891,021, which are likewise used for large door apertures, are known. A conventional sectional door consists essentially of an armor having comparatively high sections which can be circulated out of a vertical closed position into an upper horizontal position underneath the ceiling by means of a cable drive.
The comparatively large height of the individual sections which is used in sectional doors results, on account of the reduced number of connecting elements for the sections, such as hinges or the like, and also the reduction in the number of end faces to be sealed off, in a mechanically altogether more compact design having correspondingly good strength against wind forces and safety against unauthorized opening. Furthermore, the large height of the individual sections makes it possible to provide transparent portions in the form of glass or plastic windows.
The compact design of sectional doors makes it possible to provide light-weight doors composed of aluminum sections which are filled, for example, with a plastic material for heat and sound insulation, in order to make it possible to open and close garage doors, even relatively large door widths, solely by manual actuation without an additional electric-motor drive.
As a rule, the individual sections lie on one another in alignment in the closing position, so that the entire end face of a particular section is available for the sealing. The sectional door thus appears almost exactly as a closed door with a continuous outer surface, without intermediate gaps. Further--improved sealing is brought about, for example, by rubber inserts which are compressed, in the closed position, by the sections lying above one another. Alternatively, the sections have a bulge which extends on one end face of the entire door width and which engages into a corresponding depression of an adjacent section during the pivoting of the sections into the same plane as a tongue-and-groove joint, thereby further improving the mechanical strength of the door leaf against wind pressure, even where large door widths are concerned.
On the inside of the door, the sections are connected by means of a plurality of individual hinges which are mounted over the entire width of the door at particular intervals in such a number that sufficiently high strength and support is achieved. The hinges mounted on the lateral edge of the sections are typically designed at the same time as a holder for a roller which can run in a guide rail of U-shape cross-section on the edge region of the sectional door. Since the individual hinges are mounted on the sections in such a way that the sections can be folded away towards the inside, problems arise here in as much as the parts of the hinges mounted on the inside of the door and projecting are visually displeasing and afford danger of injury. A further danger of injury on sectional doors is caused during the angling of the sections, by the open gaps occurring thereby, or during the folding back of the sections and the closing of the gaps.
A further disadvantage of sectional doors having relatively high sections emerges in connection with the arcuate guide part above the lintel region, where the individual sections are articulated from the vertical position into the horizontal position. This movement naturally leads to sudden tilting accelerations and correspondingly, in response to rapid actuation, to considerable force effects on the individual sections. Acceleration and deceleration forces occur as a result of the different radial distances of the guide rollers from the actual location of the mass of the section in the region of the upper curved path, the generally non-uniform force trend resulting from the plane design of the slats of finite height, which are present in the curved path in the manner of a polygon, whereby sectional doors can be operated only at relatively low running speeds, without the risk that a relatively large amount of noise will be generated.
The transmitted transverse forces are also absorbed, by way of the plurality of individual hinges, by the body of the sections and therefore subject these body sections to load. The forces introduced into the edge hinges and correspondingly into the guide rail when the sections are being moved are essentially dependent on the speed of opening and closing of the sectional door. Because the construction is not, in principle, designed for high speeds, limits are placed on the use of sectional doors as industrial doors having a high-speed capability.
In sectional doors, a cable device with hauling cables and carrying cables and cable pulleys arranged on a drive shaft are conventionally provided as a drive system. During the upward travel of the door, the carrying cables are wound onto the cable pulleys, whilst the hauling cables are simultaneously unwound from the cable pulley. During the downward travel of the door, the hauling cables are wound up and thus pull the door down, whilst the carrying cables, without becoming slack, are simultaneously unwound from the cable pulleys. The carrying cables are thereby constantly subjected to tensile stress and cannot run down from the cable pulleys. The drive shaft is driven via an electric motor which, for example, is arranged directly underneath the ceiling.
As is known, to balance the weight of the door leaf, there are torsion springs which are arranged coaxially relative to the continuous drive shaft. In the closed position of the door, the torsion springs are fully tensioned and are correspondingly relaxed during the upward movement of the door leaf. These torsion springs are subject to increased wear and their lifetime is therefore considerably limited. Particularly in the event of a frequent and sudden reversal of direction of the cycle of movement of the sectional door, the torsion springs undergo considerable dynamic stress peaks as a result of the jolting movements. The failure of the torsion spring means that the maintenance and exchange work accompanying this in the sectional doors is time-consuming and laborious.
Because the drive shaft together with the torsion springs is arranged above the arc and the electric motor is arranged in the vicinity of the drive shaft, in conventional sectional doors it is necessary to allow for a considerable space requirement above the lintel which, without special constructive measures, for example, the provision of a double horizontal guide underneath the ceiling or the shifting of the drive shaft together with the torsion springs to the outermost end of the running rails, does not fall below a value of typically 400 mm. Added to this is the space requirement in terms of depth which is excessively high in sectional doors and which corresponds essentially to the clear height of the door aperture. Since, the free space available typically in depth, i.e., the dimension between the rear edge of the lintel and the nearest obstacle in the depth of the room, for example, joist, wall, ventilation pipe, fan or the like, will be meager in many instances the installation of the known sectional door may be impracticable.